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좌동경,홍석교,최현철 제어·로봇·시스템학회 2007 제어·로봇·시스템학회 논문지 Vol.13 No.10
This paper presents an LMI-based method to design a saturated state-feedback H2 controller for uncertain systems with actuator saturation. Specifically, the paper proposes a sufficient condition such that the system under norm-bounded uncertainties and actuator saturation is asymptotically stable and the H2-norm of the system has an upper-bound. The resulting condition is further utilized to solve a convex optimization problem specified in the context of H2-norm minimization, whose solution yields a saturated H2 controller. A numerical example is presented to show the effectiveness of the proposed method.
카메라를 이용한 3차원 공간상의 이동 목표물의 거리정보기반 모션추정
좌동경(Dongkyoung Chwa) 대한전기학회 2016 전기학회논문지 Vol.65 No.12
Range-based motion estimation of a moving object by using a camera is proposed. Whereas the existing results constrain the motion of an object for the motion estimation of an object, the constraints on the motion is relieved in the proposed method in that a more generally moving object motion can be handled. To this end, a nonlinear observer is designed based on the relative dynamics between the object and camera so that the object velocity and the unknown camera velocity can be estimated. Stability analysis and simulation results for the moving object are provided to show the effectiveness of the proposed method.
외란 보상 기법을 이용한 비선형시스템에서의 미지의 시변 사인파형 외란 보상
左東京(Dongkyoung Chwa) 대한전기학회 2007 전기학회논문지 Vol.56 No.10
This paper presents methods for the compensation of sinusoidal disturbances with unknown amplitude, phase, and time-varying frequency in nonlinear systems. In the previous disturbance accommodation methods, the sinusoidal disturbance with unknown time-invariant frequency was considered. In the proposed method, the disturbance with unknown time-varying frequency is compensated. As for the control structure, two control inputs are designed separately in such a way that one of them is designed for the nonlinear system control without considering the disturbance, and the other one uses the disturbance estimate obtained from the disturbance accommodating observer. The stability analysis is done considering the disturbance estimation error and the numerical simulation demonstrates the proposed approach.
좌동경(Dongkyoung Chwa) 대한전기학회 2016 전기학회논문지 Vol.65 No.12
In this paper, we propose an output feedback tracking control method for the wheeled mobile robots with kinematic disturbances. The kinematic disturbances should be compensated to avoid the performance degradation. Also, the unavailable velocity of the mobile robot should be estimated. These should be estimated together by designing the nonlinear observer. Based on these estimates, the output feedback controller can be designed. The stability of the mobile robot control systems using the proposed method is rigorously analyzed and the simulation results are also provided to validate the proposed method.
퍼지 기법을 이용한 다수 레이저스캐너 기반 객체 인식 알고리즘
이기룡,좌동경 한국ITS학회 2014 한국ITS학회논문지 Vol.13 No.5
본 논문에서는 레이저스캐너만으로 이루어진 감지 시스템을 이용하여 도로 위에 있는 객체의 위치를 추정하고 분류 하는 알고리즘을 제안한다. 각각의 레이저 스캐너에서 획득한 데이터는 그리드 맵을 사용하여 데이터를 융합하였으며, 팽창 연산과 레이블링 방법을 사용하여 측정 오차를 보정하였다. 추출한 객체의 정보(길이, 폭)를 입력으로 사용한 퍼지 방법을 통해 객체를 보행자, 자전거, 차량으로 분류하였으며, 이러한 방법은 레이저스캐너로만 이루어진 감지 시스템의 정확도를 증가시켰다. 또한 본 논문에서는 실제 도로 환경에서 몇 가지 시나리오를 설정하여 실험을 하였다. 실험을 통 해 감지 시스템이 객체를 정확히 분류하는지, GPS-RTK 장비를 사용하여 획득한 위치 정보와 비교하여 객체의 위치 정 보를 정확히 추정하는지 검증하였다. This paper proposes the on-road object detection and classification algorithm by using a detection system consisting of only laser scanners. Each sensor data acquired by the laser scanner is fused with a grid map and the measurement error and spot spaces are corrected using a labeling method and dilation operation. Fuzzy method which uses the object information (length, width) as input parameters can classify the objects such as a pedestrian, bicycle and vehicle. In this way, the accuracy of the detection system is increased. Through experiments for some scenarios in the real road environment, the performance of the proposed detection and classification system for the actual objects is demonstrated through the comparison with the actual information acquired by GPS-RTK.
쿨롱 마찰력 추정과 보상을 통한 역진자 시스템의 제어 성능 개선
박덕기,좌동경,홍석교 대한전기학회 2006 전기학회논문지 D Vol.55 No.11D
- When the nonlinearities, such as friction and backlash, are not considered in the controller design, undesirable oscillations can occur in the steady-state response of a control system. This paper deals with a method to reduce oscillations that often appear in the steady-state response of a pendulum system, which is controlled by a state feedback controller based on the linearized system model. With an assumption that the oscillations shown in the steady-state are caused by the Coulomb friction, we improve the performance of stabilization and tracking by estimating and compensating for the Coulomb friction in the pendulum system. Experimental results show that the control performance can be improved sufficiently by the proposed method, when it is applied to an inverted cart pendulum which is a multi-variable unstable system. Furthermore, we could see that the Coulomb friction model used in the estimation of the friction is valid in applying the suggested method.